The Swedish government, which recognised EHS as a physical impairment in 2000, calculates that 3.1 per cent of its population – 200,000 people – suffer from the condition. A recent warning by Sir William, head of the NRPB and the Health Protection Agency, that parents should limit their children's use of mobile phones received widespread publicity.

However, his suggestion that another section of the population, as well as the young, could have extra sensitivity to exposure to either radio frequency fields from mobiles or electromagnetic fields in general did not.

The NRPB has commissioned Dr Neil Irvine, of the Health Protection Agency, to carry out a review of existing scientific literature on EHS.

His report, focusing on symptoms, prognosis and treatment, will be published in the summer.

The Mobile Telecommunications and Health Research programme, funded by the Government and the telecommunications industry, is spending £8.6 million on 29 studies, two of which will investigate EHS.

A team at King's College, London, is looking at whether mobile phones cause symptoms such as headaches, nausea and fatigue in those who claim to be hypersensitive and those who do not.

Researchers at the University of Essex are exposing two groups of volunteers to signals from a mobile mast to test if cognitive functions such as attention span and memory are affected.

Dr David Dowson, a former GP who is now a complementary medicine specialist based in Bath, said he had seen around 10 patients he believed to be suffering from EHS. "I think the condition is increasing in prevalence, because we are living in a more electrically polluted environment."

Olle Johansson, associate professor of neuroscience at the Karolinska Institute in Sweden, has been studying EHS for 20 years.

He has shown in experiments that there is an increase in the number of mast cells near the surface of skin when exposed to electromagnetic fields, a similar reaction to that when it is exposed to radioactive material.

He said: "If you put a radio near a source of EMFs you will get interference. The human brain has an electric field so if you put sources of EMFs nearby, it is not surprising that you get interference, interaction with systems and damage to cells and molecules.''